Commit 93897ce1 authored Jun 20, 2019 by Suzuki K Poulose Committed by Greg Kroah-Hartman Jan 29, 2020

coresight: etb10: Do not call smp_processor_id from preemptible



commit 730766bae3280a25d40ea76a53dc6342e84e6513 upstream.

During a perf session we try to allocate buffers on the "node" associated
with the CPU the event is bound to. If it is not bound to a CPU, we
use the current CPU node, using smp_processor_id(). However this is unsafe
in a pre-emptible context and could generate the splats as below :

 BUG: using smp_processor_id() in preemptible [00000000] code: perf/2544

Use NUMA_NO_NODE hint instead of using the current node for events
not bound to CPUs.

Fixes: 2997aa40 ("coresight: etb10: implementing AUX API")
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: stable <stable@vger.kernel.org> # 4.6+
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Link: https://lore.kernel.org/r/20190620221237.3536-5-mathieu.poirier@linaro.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 564907b7

drivers/hwtracing/coresight/coresight-etb10.c

+1 −3

Original line number	Original line	Diff line number	Diff line
	@@ -279,9 +279,7 @@ static void etb_alloc_buffer(struct coresight_device csdev, int cpu,
	int node;		int node;
	struct cs_buffers *buf;		struct cs_buffers *buf;

	if (cpu == -1)		node = (cpu == -1) ? NUMA_NO_NODE : cpu_to_node(cpu);
	cpu = smp_processor_id();
	node = cpu_to_node(cpu);

	buf = kzalloc_node(sizeof(struct cs_buffers), GFP_KERNEL, node);		buf = kzalloc_node(sizeof(struct cs_buffers), GFP_KERNEL, node);
	if (!buf)		if (!buf)